Some of the largest banks in the United States may need to raise more money to protect themselves from additional economic turmoil.

The U.S. government is briefing the country's 19 largest banks Tuesday on the results of so-called "stress-tests," designed to determine how the banks would fare if the economic recession deepened.

Media reports say 10 of the 19 banks will be told to raise additional capital, although results of the "stress tests" will not be made available to the public until Thursday.

Top U.S. officials have said none of the banks will be allowed to fail, but Federal Reserve (U.S. central bank) Chairman Ben Bernanke told lawmakers Tuesday "many of the banks" will be able to raise capital without more help from the government.

Bernanke's comments were similar to those by White House spokesman Robert Gibbs. Gibbs said Monday the banks should be able to raise the funds without the help of emergency loans from the government.

The global banking sector has been hit hard by the global recession, with many banks suffering after making bad loans.

Washington has already spent more than $500 billion to help bail out troubled U.S. banks. Many investors and analysts had feared the economy could be plunged much deeper into recession if one or more major banks collapsed.

Also Tuesday, one of the banks subject to the U.S. government "stress test" posted a major loss.

GMAC said it lost $675 million for the first three months of this year due, in part, to bad loans.

GMAC is the lending arm of struggling U.S. auto giant General Motors. GMAC has already gotten $5 billion as part of the U.S. government bank bailout plan.

Meanwhile, Swiss banking giant UBS is warning there could be more trouble in the months to come.

UBS said it lost $1.75 billion during the first quarter because of bad loans and because some customers are pulling their money out of the bank.